The disclosure relates to an internal gear pump for a hydraulic vehicle brake system. The internal gear pump is provided in particular for use in a slip-controlled and/or power-operated vehicle brake system instead of a piston pump usually used therein, which is often, though not necessarily accurately, referred to as a return pump.
The laid-open application DE 195 17 296 A1 discloses an internal gear pump having an annulus and having a pinion which is arranged eccentrically in the annulus such that it meshes with the annulus. The pinion is arranged for conjoint rotation on a pump shaft which serves to drive the pinion in rotation. When driven in rotation, the pinion drives the annulus, with which said pinion meshes, in conjoint rotation, with the result that the internal gear pump is driven and delivers fluid in a manner known per se. The pinion is an externally toothed gearwheel and the annulus is an internally toothed gearwheel, which are referred to here as pinion and annulus for unambiguous designation and to distinguish between them.
At the circumference, the pinion and the annulus delimit, toward the inside and toward the outside, a crescent-shaped pump space between one another, said pump space being covered laterally by rotationally fixed axial disks which bear in a sealing manner against end sides of the pinion and of the annulus. The lateral sealing is not hermetically sealed, the axial disks bear in the manner of plain bearings against the end sides of the pinion and of the annulus, and limited leakage is acceptable. An optimum between low friction and low leakage should be found.
In the circumferential direction, the axial disks extend at least over a pressure region of the pump space. In the axial direction, the axial disks are pressurized on their outer side remote from the pinion and the annulus in what are known as pressure fields and, as a result, are urged into contact against the end sides of the pinion and of the annulus. The pressure field is a usually shallow depression which extends approximately over the pump space or the pressure region of the pump space. Such axial disks are also referred to as pressure disks or control disks or as pressure plates or control plates. They are typically in the form of disks or plates, although this is not essential for the disclosure.